Air fuel ratio gauge options

I use an AEM wideband where the controller is in the gauge so you could just unplug that connector and remove it when you didn't want it in there. Similar to this one:
AEM Electronics 30-4110 AEM Electronics Wideband Air/Fuel UEGO Gauge Kits | Summit Racing

They use the Bosch wideband sensor and they are stock on a lot of modern cars so you can leave it in there and expect it to last thousands and thousands of miles so long as you don't run leaded fuel.